This invention relates to a check valve for hydraulic self-regulating device pistons which is particularly applicable to hydraulic self-regulating devices for regulating the length of control cables.
The known hydraulic self-regulating devices for compensation of variations of control cable lengths are constituted, in general, by an essentially cylindrical main hollow body containing a piston, a liquid fluid, a regulating rod attached at one end to the corresponding end of the control cable and a regulating spring which exerts a permanent pull on the control cable by way of the regulating rod.
Spanish patent P 9002014 discloses a hydraulic self-regulating device in which the regulating rod extends out from one end of the main body and is connected to the corresponding end of the control cable and the other end of the rod, which remains housed in the main body, is attached to a piston comprising a check valve which may have different embodiments. This piston defines in the main body two half-chambers respectively located one on each side of the piston.
One embodiment of said check valve disclosed in Spanish patent P 9002014 comprises a flow body, a stopper body and an opening spring. The flow body is attached to the regulating rod and is provided with orifices forming a communication between the two half-chambers defined in the main body by the piston, the flow body also having a perimetrical sealing gasket. The stopper body is coaxially disposed around the regulating rod and may slide in both directions so that, by means of a sealing gasket, it may open or close the flow body orifices. And the opening spring is permanently under compression and is arranged coaxially around the regulating rod between the flow body and the stopper body while bearing against the respective opposed faces.
In general, both the above described embodiment and the remaining embodiments of the piston check valve disclosed in Spanish patent P 9002014 suffer from the drawback of being formed by a large number of expensive-to-make components, which increases both the production costs and the assembly costs of the valve and, consequently, of the self-regulating device.